SensorDisc - a novel approach to in-situ assessment of bolt load and condition.

Abstract

While Structural Health Monitoring has become widespread and well-accepted for ensuring safety and longevity of buildings and facilities, the condition of fasteners in said structures is oftentimes not considered for holistic condition assessment. This is not representative of the role fixings (in particular, bolt connections) play, as they experience high loads, fatigue, and corrosion, with the potential for causing costly consequences in case of failure. In practice, the condition assessment of bolts is usually carried out by periodic re-tightening and manual documentation of the torque and apparent condition. This procedure is not only labor-intensive but also fails to provide deeper insights into the condition of the bolted connection itself. Furthermore, in many cases, the inspection intervals are not tailored to the specific needs of projects and structures but are based on general assumptions, which necessarily represent a compromise between costly over-caution and accepting blind spots. One possible reason for not making more widespread use of monitoring technology in this case is the high cost and complexity of conventional bolt monitoring, where individual bolts are manually fitted with load sensors, and data processing is performed by highly skilled professionals. A solution for this dilemma is presented in the form of the fischer SensorDisc, which offers a fully integrated, robust, and convenient option for bolt load assessment. One of the key features that distinguish the SensorDisc is its dedicated design for use in industrial and construction environments. Not only can it be used in a variety of bolt connections, either as original equipment or as a retrofit, but it also does not require special tools for readout, as this can be accomplished with a common smartphone. For maximized ease of use, data and device management are all offered through a cloud-based service that can be accessed via an app, browser, or API.